/*
    * Copyright 2016-2022 The OSHI Project Contributors
    * SPDX-License-Identifier: MIT
    */
   package oshi.hardware.platform.mac;
   
   import java.util.ArrayList;
   import java.util.List;
   
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import com.sun.jna.Pointer;
  import com.sun.jna.platform.mac.CoreFoundation.CFDataRef;
  import com.sun.jna.platform.mac.CoreFoundation.CFStringRef;
  import com.sun.jna.platform.mac.CoreFoundation.CFTypeRef;
  import com.sun.jna.platform.mac.IOKit.IOIterator;
  import com.sun.jna.platform.mac.IOKit.IORegistryEntry;
  import com.sun.jna.platform.mac.IOKitUtil;
  
  import oshi.annotation.concurrent.Immutable;
  import oshi.hardware.Display;
  import oshi.hardware.common.AbstractDisplay;
  
  /**
   * A Display
   */
  @Immutable
  final class MacDisplay extends AbstractDisplay {
  
      private static final Logger LOG = LoggerFactory.getLogger(MacDisplay.class);
  
      /**
       * Constructor for MacDisplay.
       *
       * @param edid a byte array representing a display EDID
       */
      MacDisplay(byte[] edid) {
          super(edid);
          LOG.debug("Initialized MacDisplay");
      }
  
      /**
       * Gets Display Information
       *
       * @return An array of Display objects representing monitors, etc.
       */
      public static List<Display> getDisplays() {
          List<Display> displays = new ArrayList<>();
          // Iterate IO Registry IODisplayConnect
          IOIterator serviceIterator = IOKitUtil.getMatchingServices("IODisplayConnect");
          if (serviceIterator != null) {
              CFStringRef cfEdid = CFStringRef.createCFString("IODisplayEDID");
              IORegistryEntry sdService = serviceIterator.next();
              while (sdService != null) {
                  // Display properties are in a child entry
                  IORegistryEntry properties = sdService.getChildEntry("IOService");
                  if (properties != null) {
                      // look up the edid by key
                      CFTypeRef edidRaw = properties.createCFProperty(cfEdid);
                      if (edidRaw != null) {
                          CFDataRef edid = new CFDataRef(edidRaw.getPointer());
                          // Edid is a byte array of 128 bytes
                          int length = edid.getLength();
                          Pointer p = edid.getBytePtr();
                          displays.add(new MacDisplay(p.getByteArray(0, length)));
                          edid.release();
                      }
                      properties.release();
                  }
                  // iterate
                  sdService.release();
                  sdService = serviceIterator.next();
              }
              serviceIterator.release();
              cfEdid.release();
          }
          return displays;
      }
  }